The Great Divide, one of many fissures in the land caused by the Cataclysm

The Shattering (also called the Second Sundering and Cataclysm) was a worldwide disaster that struck Azeroth following Deathwing blasting his way from Deepholm into the world. Earthquakes, volcano eruptions, and floods followed in his wake, reshaping the face of the world.

Consequences

The coastlines of Kalimdor and the Eastern Kingdoms shifted, flooding some old lands and exposing new ones. Whole parts of the world, like Thousand Needles and a large chunk of Tanaris, ended up underwater. In some cases, tidal waves caused by the Cataclysm flooded or destroyed coastal settlements like Auberdine, Rut'theran Village, and Feathermoon Stronghold, forcing their residents to relocate — usually inland. Even far from the coast, fires, avalanches and lava eruptions changed some areas beyond recognition.

The tectonic shifts blocked some old routes, like the one between Badlands and Loch Modan, and opened some new ones through previously impassable mountains. The Shattering also damaged an ancient titan device previously hiding the Uldum complex, exposing access to it from Tanaris.

The goblin island of Kezan and the self-isolated nation of Gilneas suffered greatly from natural disasters, leading directly to events that affected the existing balance between the Alliance and the Horde, redrawing the political map of the world.

In-game

This section concerns content introduced with the Shattering and changes after the Cataclysm that do not require the expansion to experience.